1.4.33

1.4.33

Released: March 31, 2022

orm

• [orm] [usecase] Added _orm.with_polymorphic.adapt_on_names to the
  _orm.with_polymorphic() function, which allows a polymorphic load
  (typically with concrete mapping) to be stated against an alternative
  selectable that will adapt to the original mapped selectable on column
  names alone.

  References: #7805

• [orm] [usecase] Added new attributes UpdateBase.returning_column_descriptions and
  UpdateBase.entity_description to allow for inspection of ORM
  attributes and entities that are installed as part of an Insert,
  Update, or Delete construct. The
  Select.column_descriptions accessor is also now implemented for
  Core-only selectables.

  References: #7861

• [orm] [performance] [bug] Improvements in memory usage by the ORM, removing a significant set of
  intermediary expression objects that are typically stored when a copy of an
  expression object is created. These clones have been greatly reduced,
  reducing the number of total expression objects stored in memory by
  ORM mappings by about 30%.

  References: #7823

• [orm] [bug] [regression] Fixed regression in "dynamic" loader strategy where the
  _orm.Query.filter_by() method would not be given an appropriate
  entity to filter from, in the case where a "secondary" table were present
  in the relationship being queried and the mapping were against something
  complex such as a "with polymorphic".

  References: #7868

• [orm] [bug] Fixed bug where _orm.composite() attributes would not work in
  conjunction with the _orm.selectin_polymorphic() loader strategy for
  joined table inheritance.

  References: #7801

• [orm] [bug] Fixed issue where the _orm.selectin_polymorphic() loader option would
  not work with joined inheritance mappers that don't have a fixed
  "polymorphic_on" column. Additionally added test support for a wider
  variety of usage patterns with this construct.

  References: #7799

• [orm] [bug] Fixed bug in _orm.with_loader_criteria() function where loader
  criteria would not be applied to a joined eager load that were invoked
  within the scope of a refresh operation for the parent object.

  References: #7862

• [orm] [bug] Fixed issue where the _orm.Mapper would reduce a user-defined
  _orm.Mapper.primary_key argument too aggressively, in the case
  of mapping to a UNION where for some of the SELECT entries, two columns
  are essentially equivalent, but in another, they are not, such as in a
  recursive CTE. The logic here has been changed to accept a given
  user-defined PK as given, where columns will be related to the mapped
  selectable but no longer "reduced" as this heuristic can't accommodate for
  all situations.

  References: #7842

engine

• [engine] [usecase] Added new parameter Engine.dispose.close, defaulting to True.
  When False, the engine disposal does not touch the connections in the old
  pool at all, simply dropping the pool and replacing it. This use case is so
  that when the original pool is transferred from a parent process, the
  parent process may continue to use those connections.

  References: #7815, #7877

• [engine] [bug] Further clarified connection-level logging to indicate the BEGIN, ROLLBACK
  and COMMIT log messages do not actually indicate a real transaction when
  the AUTOCOMMIT isolation level is in use; messaging has been extended to
  include the BEGIN message itself, and the messaging has also been fixed to
  accommodate when the Engine level
  create_engine.isolation_level parameter was used directly.

  References: #7853

sql

• [sql] [usecase] Added new parameter
  FunctionElement.table_valued.joins_implicitly, for the
  FunctionElement.table_valued() construct. This parameter indicates
  that the given table-valued function implicitly joins to the table it
  refers towards, essentially disabling the "from linting" feature, i.e. the
  "cartesian product" warning, from taking effect due to the presence of this
  parameter. May be used for functions such as func.json_each().

  References: #7845

• [sql] [bug] The bindparam.literal_execute parameter now takes part
  of the cache generation of a bindparam(), since it changes
  the sql string generated by the compiler.
  Previously the correct bind values were used, but the literal_execute
  would be ignored on subsequent executions of the same query.

  References: #7876

• [sql] [bug] [regression] Fixed regression caused by #7760 where the new capabilities of
  TextualSelect were not fully implemented within the compiler
  properly, leading to issues with composed INSERT constructs such as "INSERT
  FROM SELECT" and "INSERT...ON CONFLICT" when combined with CTE and textual
  statements.

  References: #7798

schema

• [schema] [usecase] Added support so that the Table.to_metadata.referred_schema_fn
  callable passed to Table.to_metadata() may return the value
  BLANK_SCHEMA to indicate that the referenced foreign key should be
  reset to None. The RETAIN_SCHEMA symbol may also be returned from
  this function to indicate "no change", which will behave the same as
  None currently does which also indicates no change.

  References: #7860

sqlite

• [sqlite] [bug] [reflection] Fixed bug where the name of CHECK constraints under SQLite would not be
  reflected if the name were created using quotes, as is the case when the
  name uses mixed case or special characters.

  References: #5463

mssql

• [mssql] [bug] [regression] Fixed regression caused by #7160 where FK reflection in
  conjunction with a low compatibility level setting (compatibility level 80:
  SQL Server 2000) causes an "Ambiguous column name" error. Patch courtesy
  @Lin-Your.

  References: #7812

misc

• [bug] [ext] Improved the error message that's raised for the case where the
  association_proxy() construct attempts to access a target attribute
  at the class level, and this access fails. The particular use case here is
  when proxying to a hybrid attribute that does not include a working
  class-level implementation.

  References: #7827